WO2016131857A1

WO2016131857A1 - Method and apparatus for friction welding

Info

Publication number: WO2016131857A1
Application number: PCT/EP2016/053339
Authority: WO
Inventors: Manfred Menzinger; Stefan Ohm; Andreas Klett; Walter Weh; Erwin VÖTTERL
Original assignee: Kuka Industries Gmbh
Priority date: 2015-02-19
Filing date: 2016-02-17
Publication date: 2016-08-25
Also published as: US20180036834A1; CN107249808A; DE102015102353A1; EP3259094A1

Abstract

The invention relates to a method and apparatus for friction welding of workpieces (2, 3), which are softened and welded in a friction phase (R) with frictional contact and under frictional pressure (p) in a relative rotational movement about a process axis (8) through the effect of frictional heat. The frictional pressure (p) applied during axial advancement of one of the workpieces (3) is preferably ramped and increased during the friction phase (R).

Description

DESCRIPTION

Method and apparatus for friction welding

The invention relates to a method and apparatus for friction welding of workpieces having the features in the preamble of the process and

Device main claim.

Such methods and devices for friction welding are known in practice. They are used for workpieces with relatively small diameters. In the friction phase, a constant friction pressure is used.

It is an object of the present invention to provide a

show improved friction welding technology.

The invention solves this problem with the features in the method and device main claim.

A basic aspect of the invention provides that the

Friction pressure (p) during the duration of the friction phase (R)

is changed and increased. The pressing device of the friction welding device can be controlled accordingly. The specified pressure range with the change and

Increase between about 4 N / mm ² and 100 N / mm ²

advantageous. The pressure range with the increase of initially about 5 N / mm ² to 80 N / mm ² is particularly favorable. Alternatively, under the said basic aspect, there may be other pressure ranges, in particular higher end values of the friction pressure. The features in the subclaims may relate to said basic aspect. They have particular advantages in connection with the specified pressure ranges, whereby they can also be used for other pressure ranges and thus combined. The friction welding technique, ie the method and the

Device for friction welding, have the advantage that by changing and increasing the friction pressure during the friction phase, the heat conditions and heat influences in the process can be additionally and better controlled and optimized. In particular, by the increasing friction during the friction phase, the heat input and the temperature profile close to the contact and

Joint between the workpieces in such a way

be influenced that the effecting on the hardening maximum temperature and the

Cooling speed can be positively influenced.

A reduction in the components occurring in the components

Maximum temperature has advantages for the structure formation in metallic workpieces, in particular those made of steel with a higher carbon content, which tend to harden and embrittle at higher cooling rate. The latter can be unfavorable for the strength and the service life, especially for friction-welded components with dynamic loading. With the reduced

Cooling rate, such hardening and dynamic strength problems can be avoided or at least substantially reduced. The friction pressure increase can be attributed to the heating and cooling properties of the

Workpiece materials are adjusted.

It has proven to be advantageous if the friction pressure is increased continuously or continuously during the friction phase. This can be done in the form of a linear ramp, which in particular for workpieces made of steel with higher

Carbon content is beneficial. Alternatively, a Reibdruckerhöhung can be done stepwise or staircase-like. Furthermore, wave-like pressure fluctuations during the Reibdruckerhöhung are possible. It has also been found to be favorable when the friction pressure is changed and increased during most or all of the friction phase. In particular, from an initially low pressure level out of the

Pressure increase delayed or use with a time offset. At the end of the friction phase, the friction pressure is higher than at the beginning.

The claimed Reibschweißtechnik has other advantages. In particular, it allows the friction welding of

Workpieces with a significantly larger effective diameter at the point of contact and connection than hitherto customary. The workpieces may have a frictional diameter of 200 mm or more, preferably 500-650 mm.

Moreover, it can be significantly increased with a high speed and one over the prior art

Peripheral speed in the relative movement of

Workpieces at the contact and connection point

to be worked. The workpieces may, during the rubbing phase (R) at the point of contact, e.g. with a

Peripheral speed of 5 m / sec or more, preferably 12-17 m / sec, are rotated relative to each other. The friction pressure (p) and the drive speed can be adjusted and adjusted accordingly during the duration of the friction phase (R). The Reibscheißvorrichtung can

be controlled accordingly. The low initial pressure causes the still rigid contacting

Workpiece edges a correspondingly low

Frictional resistance. With increasing friction heating and

Plasticizing the workpiece edges, the friction pressure can be increased. The workpieces are advantageously designed as tubes or have at least one tubular section in the region of the friction-welded connection. By the claimed Reibdruckerhöhung weaker rotary actuators of Reibschweißvorrichtung can be used or alternatively workpieces with a significantly larger diameter at the contact and connection point

be friction welded. In the known

Reibschweißtechnik with the very high initial and during the friction phase constant friction pressure would be too high for normal rotary actuators workpieces with large Reibschweißdurchmessern the moment of resistance, so that either such workpieces can not be friction-welded or this is a very special and

Oversized friction welding device is required. By the claimed Reibdruckerhöhung starting with a much lower initial pressure can

Resistance torque at the beginning of the friction phase are reduced so much that the rotary drive of a conventional

Friction welding machine can start. The friction welding pressure can then be gradually increased, the

Moment of inertia of the current rotary drive and / or the masses is sufficient to overcome the increased resistance and to maintain the required for the friction heating of the workpieces relative rotation and heat input. In the start-up phase, it may also be beneficial to first keep the low friction pressure constant for a certain time and only then to increase it. Here also a linear ramp function is advantageous. In the friction welding technique according to the invention, despite the large workpiece diameter, a high speed of e.g. about 500 U / min to be worked. This leads to much higher because of the diameter size

Circumferential speeds at the contact and

Connection area. Advantageously, with a preferably slow Reibdruckanstieg and a high peripheral speed only a narrow contact and Liquefied connection area, whereby also melted material particles can be ejected. This is a heat loss and a homogenization of workpiece heating and a reduction of the

Maximum temperature at the contact and connection area associated. These effects are favorable for the

Friction welding process and the heat and energy balance and the beneficial uniform material and

Structure formation in the friction-welded connection area. Also, the aforementioned cooling rate and the

Preventing hardening and embrittlement is positively supported by this effect.

The friction welding device may have a control, with the implementation of the claimed method, a pressing device and a rotating device of the

Friction welding device are driven accordingly. The controller can be programmable and can

in particular, include a friction welding program. In addition, a technology database may be associated with which the friction welding parameters for a wide variety of

Workpiece pairings or calculation bases for the generation and calculation of such friction welding parameters contains. In addition, a control or regulation of the axial feed paths and Reibschweißverkürzungen and the total length of the finished welding part can be done.

The workpieces, especially those with very large ones

Reibschweißdurchmessern, are formed as tubes. They are fastened in a workpiece holder in a suitable manner, in particular by means of a clamping device. For the transmission of high torque large radial clamping pressures are required, which load the workpiece. The claimed arrangement of a support device supports these clamping pressures and avoids deformations of the workpiece. The claimed Reibschweißtechnik is especially for a rotating and circumferential relative movement of the workpieces of advantage. It can alternatively be used with appropriate adaptation in other friction welding techniques and kinematics of relative movement, in which, for example, the

Relative movement is oscillating and / or a linear component of motion and / or a pendulum motion or the like is present. in the subclaims are further advantageous

Embodiments of the invention indicated.

The invention is illustrated by way of example and schematically in the drawings. In detail show:

Figure 1: a Reibschweißvorrichtung

schematic representation,

Figure 2: a diagram for the speed and

Reibdruckverlauf over time according to

Invention and

Figure 3: a diagram for the speed and

Reibdruckverlauf according to the prior art.

The invention relates to a method and a device (1) for the friction welding of workpieces (2, 3).

The workpieces (2, 3) can be of any type and size and can be made of any kind suitable for friction welding

Consist of materials. Preferably, the workpieces are designed as tubes or have at least one tubular section in the region of the friction-welded connection. Preferably, the workpieces (2,3) made of metal. In the following embodiments, they are made of steel with a higher carbon content, which tends to harden at a higher cooling rate.

In principle, the workpieces (2, 3) can consist of the same or a different material.

Differences may be particularly in terms of

Melting temperature and the thermal conductivity may be present. For example, material pairings of steel with cast materials, in particular metal casting with

Graphite inclusions, of ferrous and non-ferrous metals and the like. be friction welded. In addition, non-metallic friction welding partners are possible. In the embodiment shown, the workpieces (2,3) have a very large effective diameter at the contact and connection point (4). This diameter is 200 mm or more. Preferably, the

Diameter over 350 mm, more preferably in the range between 500 mm and 650 mm.

For friction welding, the workpieces (2, 3) to be joined are moved axially against one another along a central process axis (8) and pressed against them

Process axis (8) relative to each other and rotated circumferentially. During the relative rotation, the workpieces (2, 3) are pressed axially against one another at the contact and connection point (4) with a certain friction pressure (p). Due to the frictional resistance, heat in the contact and

Joint introduced (4), which leads to the heating and melting of the workpieces (2,3) in this area. Subsequently, the workpieces (2,3) are pressed together with a compression stroke, the relative rotation is terminated before or simultaneously.

At the beginning of the friction welding process, the workpieces (2, 3) are axially distanced, whereby the rotational movement of the one workpiece (2) starts. Then the workpieces (2,3) are axially approximated and brought into touching contact during feed, wherein by the axial pressure force (F) at the peripheral contact and connection region (4) a

Friction pressure (p) is applied. In this variant, a flying start of the feed takes place in the already rotating workpiece (2). The beginning of the pressure increase with workpiece contact signals the actual position to

welding workpiece front edges and is in the

Evaluation stored as a so-called zero position. The zero position is for the control of the

Feed paths and the desired final length of the welding part and the workpiece shortening significant. In another variant, the workpieces (2, 3) can first be brought into touching contact without relative rotation in order to detect the said zero position and the actual position via the increase in pressure. Then they are again distanced a piece, the relative rotation starts and at the same time the axial feed takes place. In both variants, the target speed (n) is reached when touched.

From the contact contact with relative rotation, the friction phase (R) starts in which the workpiece edges at the contact and connection area (4) under the friction pressure (p) are plasticized by the heat and optionally a

Reibwulst radially at the point (4) is formed and the workpieces (2,3) are further axially approximated to each other accordingly. At the end of the friction phase, the

Relative rotation or the rotating workpiece (2,3)

be braked, at the same time or shortly thereafter, the axial pressure force (F) is significantly increased in a so-called compression stroke.

FIG. 3 shows a diagram of the course of the friction pressure (p) and of the rotational speed (n) according to the known prior art in an application for large diameters and conventional friction

Peripheral speeds of about 3 m / sec. with a correspondingly dimensioned friction welding device. The friction pressure (p) is already very high at the beginning of the friction phase (R) and remains constant during the friction phase. A conventional pressure value is for example about 80 N / mm ² . The nominal or rated speed (n) is also constant after a start phase and is approx. 100 rpm. Such a friction welding method with the conventional welding parameters (p, n) requires a very strong rotary drive and an oversized

Machine design. The diagram of Figure 2 illustrates the Reibschweißverfahren invention. The embodiment shown here refers to workpieces (2,3) made of steel, in which at least one workpiece (2,3) increased

Has carbon content and is prone to harsh. The friction-effective diameter of the workpieces (2,3) is 560 mm. At the beginning of the friction phase (R), the friction pressure (p) is significantly lower than in the prior art. It is for example at about 5 N / mm ² . It initially stays at this low level for a certain amount of time and then ramps up and linearly up to a friction pressure of eg 80 N / mm ² at the end of the friction phase (R).

The offset or the time delay up to the beginning of the pressure increase can with the start phase to

Reaching the target or rated speed (s) correlate. As soon as the setpoint speed is reached, so does the

Friction pressure (p). At the end of the friction phase (R), the friction pressure is approximately the same as in the prior art according to FIG. 3.

According to Figure 2 is in the inventive

Friction welding also the rated speed (s) of the

Rotary drive (6) higher than in the prior art of Figure 3. It is about 500 U / min. After completion of the start phase, it also remains constant until the end of the friction phase (R) and then preferably abruptly

slowed down.

In this embodiment results in the target ^¬ or rated speed (n) at the contact and connection area (4) has a peripheral speed of about 14.4 m / sec. It is much higher than in the prior art, where it is about 1 to 5 m / sec. For other embodiments and friction welding pairings, other parameters may result. Preferably, the friction pressure (p) is increased in a range between about 4 N / mm ² and 100 N / mm ² in the friction phase. At the end of

Frictional phase, the friction pressure is definitely higher than

Beginning. Deviating from the embodiment shown, the friction pressure (p) in one or more stages and

possibly also increase with stair-like jumps or with a stepped ramp function. During the friction phase (R), the friction pressure (p) is preferably continuously or continuously changed and increased. The pressure increase can also be in a non-linear curve function

run. According to the variable friction effective diameter, the peripheral speeds at the contact and

Connection area (4) vary. They are preferably at or above 5 m / sec. A range between 12 and 17 m / sec is preferred. The specified speed (n) can

be varied accordingly.

The aforementioned embodiment and the modifications relate to the friction welding with a

continuous motor drive for the

Relative movement and active braking of the motor drive. You can use for flywheel welding

Moment of inertia and switched off rotary drive

look different accordingly. in the shown and preferred embodiment, the Reibschweißvorrichtung (1) on a frame (5) on which a machine head with a rotating means (6) and a coupled workpiece holder (10) for the one workpiece (2) is arranged stationary or axially movable. Further, a pressing device (7) with a workpiece holder (11) for the other workpiece (3) is arranged on the frame (5). It can, for example, according to Figure 1 the machine head be arranged axially opposite one another.

In the embodiment shown, two workpieces (2,3) are friction welded. In other and not shown modifications so-called double-head friction welding machines are possible in which three or more workpieces are friction-welded together in one process.

The rotating device (6) has in the shown

Embodiment, a drive motor which rotates the arranged on a spindle workpiece holder (10) to the process axis (8). This can be a direct drive or an intermediate gear drive. The rotating device (6) may further comprise a braking device.

In another embodiment, not shown, the rotary drive can be designed as a flywheel drive, in which the drive motor sets a flywheel in rotation about the process axis (8), which then in

Friction welding process brings the required kinetic energy.

The drive motor is in different

Embodiments preferably designed as a controllable and possibly adjustable electric motor. He can as

DC motor or AC motor, in particular as a three-phase motor, be formed. The pressing device (7) ensures the axial approach of the workpieces (2, 3) over the path (s) and the pressing force or friction force (F) acting thereby. The

Pressing device (7) can be designed and arranged in any suitable manner for this purpose. It can generate axial tensile or compressive forces. In the illustrated and preferred embodiment, it is designed as a feed device (14). This has a feed drive (15) for the advance of the

Workpiece holder (11) along the process axis (8). The feed drive is e.g. designed as a hydraulic cylinder. Alternatively, as another linear drive, in particular as an electric spindle drive or the like. be educated. The feed drive (15) is controllable and also controllable in conjunction with a suitable force and / or wegaufnehmenden sensor.

In the embodiment shown, the e.g. stationary on the frame (5) arranged and supported feed drive (15) by means of a rod-like feed member on an axially movable on the frame (5) mounted bracket (16).

The workpiece holder (11) is fixedly or releasably attached to the holder (16).

The workpiece holders (10,11) can in any

be suitably trained. In the shown

Embodiments, they are equipped with a clamping device (12), which respectively clamps the workpiece (2,3) radially from the outside or inside. The

Clamping device (12) may e.g. have a chuck with two or more radially adjustable jaws.

In order to support the clamping forces, a support device (13) can be arranged on a workpiece (2, 3) which opposes and counteracts the clamping device (12), wherein it supports the clamping forces and the workpiece (2, 3).

supported. The support means (13) is e.g. arranged in the rotating workpiece (2), but can also be located on both or all workpieces (2,3). It can through the cavity of the workpiece (2,3) with the respective

Tool holder (10,11) connected and held. The friction welding device (1) has a preferably programmable logic controller (9) which is connected to the various machine components,

in particular with the rotary drive (6) and the

Feed drive (15) and with a sensor, which in the friction welding of the Reibschweißpartnern

the paths taken and the forces acting on them. The controller (9) controls the friction welding device (1) and its components in a corresponding manner to

Implementation of the aforementioned friction welding process. It may include one or more stored friction welding programs. It can also be a technology database with finished or to be calculated Reibschweißparametern and a suitable arithmetic unit together with on and

Have output interfaces.

Modifications of the above-described embodiments and the variants mentioned are possible in any way. In particular, the characteristics of the various

Embodiments and variants are arbitrarily combined with each other and possibly also reversed.

In particular, another kinematics of the relative movement between the workpieces (2,3) and a correspondingly different structural design of the friction welding device (1) is possible.

In other Reibschweißvorrichtungen, in particular

Double-head friction welding devices, are

Multiple arrangements of the rotary drive (6) and another structural design of the pressing device (7) possible. In particular, one of the pressing device (7) advanced support (16) include a rotary drive (6), wherein between the rotating workpieces one or more further and preferably relatively non-rotatably held workpieces are arranged. The

Pressing device (7) can also axially with both sides be connected to movable machine heads and move them axially and against each other and against a central support for a third or more workpieces. A pressing device (7) can also be modified from FIG. 1 in a single-head friction welding machine

on the output side on a stationary holder (16)

support, wherein the said machine head during axial feed relative to the on a stationary support (16) located workpiece (3) is moved. In a

Embodiment, a feed device (14) are formed by cylinder with Gehauseanbindung on this axially movable machine head or headstock. The friction welding device (1) can in particular also be designed as a double single-head friction welding machine which has a common central and stationary support device or holder (16) with workpiece holders (11) on both sides and a mirror-image arrangement of

Having machine heads, each with its own rotary drive (6) together with pressing device (7). A pressing device (7) can in this and in other embodiments on the stationary or axial shown in Figure 1

Movable machine head with the rotary drive (6)

be arranged and exercise traction.

LIST OF REFERENCE NUMBERS

1 friction welding device

2 workpiece

3 workpiece

4 contact point, connection area

5 frame

6 rotating device

7 pressing device

8 process axis

9 control

10 workpiece holder

11 workpiece holder

12 clamping device

13 support device

14 feed device

15 feed drive, cylinder

16 bracket

F pressing force, compression force, friction force p friction pressure

n speed

s feed path

R friction phase

S compression phase

Claims

1.) Process for friction welding of workpieces (2,3), in a friction phase (R) under frictional contact and with a friction pressure (p) in a relative movement, in particular a relative rotation about one

Process axis (8), plasticized by friction heat and welded, thereby

characterized in that the friction pressure (p) during the period of the friction phase (R) in a range between about 4 N / mm ² and 100 N / mm ^{2 is} changed and increased.

2.) Process according to claim 1, characterized

e, that the workpieces (2,3) are formed as tubes or at least one tubular portion in the region of

Reibschweißverbindung have.

A method according to claim 1 or 2, characterized

e, that the friction pressure (p) during the friction phase (R) continuously, and in particular in a linear ramp, changed and increased. 4.) The method of claim 1, 2 or 3, characterized

e, that the friction pressure (p) during the greater part or the whole

Frictional phase (R) is continuously changed and increased.

5.) Method according to one of the preceding claims, characterized in that the

Friction pressure (p) during the friction phase (R) of

initially 5 N / mm ^{2 is increased} to 80 N / mm ² . Method according to one of the preceding claims, characterized in that the

Friction pressure (p) along the process axis (8)

is applied.

Method according to one of the preceding claims, characterized in that the

Workpieces (2,3) following the friction phase (R) in a compression phase (S) with an elevated

Pressing force (F) are pressed axially against each other.

Method according to one of the preceding claims, characterized in that workpieces (2, 3) with a friction-effective diameter of 200 mm or more, preferably 500-650 mm, are friction-welded.

Method according to one of the preceding claims, characterized in that workpieces (2, 3) made of metal, in particular of steel with a higher carbon content, are friction-welded.

10.) Method according to one of the preceding claims, characterized in that the

Workpieces (2,3) during the friction phase (R) are rotated relative to each other at a speed (n) of about 500 U / min. 11.) Method according to one of the preceding claims, characterized in that the

Workpieces (2,3) during the friction phase (R) at the contact point (4) with a circumferential speed of 5 m / sec or more, preferably 12-17 m / sec, are rotated relative to each other.

12.) Device for friction welding of workpieces (2,3), in a friction phase (R) under frictional contact and the action of a pressing force (F) in one

Relative movement, in particular a relative rotation about a process axis (8), plasticized and welded by frictional heat, wherein the friction welding device (1) workpiece holders

(10,11), a relative movement device (6), in particular a rotating device, and a

Pressing device (7) for the workpieces (2,3) and a controller (9), characterized

There is no such thing as the

Pressing device (7) is controlled such that the friction pressure (p) during the duration of the friction phase (R) in a range between about 4 N / mm ² and 100

N / mm ^{2 is} changed and increased.

13.) Friction welding device according to claim 12, characterized

There is no such thing as the

Pressing device (7) is controlled such that the friction pressure (p) during the period of the friction phase (R) of initially 5 N / mm ² to 80 N / mm ^{2 is} increased. 14.) Friction welding device according to claim 12 or 13, characterized in that the

Friction pressure (p) during the friction phase (R) steadily, in particular in a linear ramp, is increased. 15.) Friction welding device according to claim 12, 13 or 14, characterized in that it e e n e c i n e t that the

Pressing device (7) is controlled such that the friction pressure (p) during the largest part or the entire friction phase (R) is continuously changed and increased.

16). Friction welding device according to one of claims 12 to 15, characterized in that the rotating device (6) and the pressing device (7) are arranged along the central process axis (8).

are arranged and act.

17.) Friction welding device according to one of claims 12 to 16, characterized g e k e n n e c i n e t that the pressing device (7) is controlled such that the workpieces (2,3) following the

Frictional phase (R) in a compression phase (S) with an increased compression force (FS) are pressed axially against each other. 18.) Friction welding device according to one of claims 12 to 17, characterized in that the friction welding device (1) for workpieces (2,3) with a friction effective diameter of 200 mm or more, preferably 500 - 650 mm, is designed.

19.) Friction welding device according to one of claims 12 to 18, characterized in that the friction welding device (1) for workpieces (2,3) made of metal, in particular made of steel with a higher carbon content, is designed.

20.) Reibschweißvorrichtung according to any one of claims 12 to 19, characterized in that the rotating means (6) is controlled such that the workpieces (2,3) during the friction phase (R) at a speed (n) of about 500 U / min relative

be turned to each other.

21.) Friction welding device according to one of claims 12 to 20, characterized in that the rotary device (6) is controlled such that the workpieces (2,3) during the friction phase (R) the contact point (4) with a

Peripheral speed of 5 m / sec or more, preferably 12-17 m / sec, are rotated relative to each other. Friction welding device according to one of claims 12 to 21, characterized in that the friction welding device (1) is designed for workpieces (2, 3) which are designed as tubes or have at least one tubular section in the region of the friction-welded connection. Friction welding device according to one of claims 12 to 22, characterized in that a workpiece holder (10, 11) comprises a clamping device

(12) and one on the workpiece (2,3) can be arranged

Supporting device (13) for supporting the workpiece (2,3) against the clamping forces.